Abstract: A quantum random number generator is provided that can generate more secure random numbers in consideration of at least one of imperfection of quantum bits or imperfection of a projective measurement equipment. In this generator, the functional configuration of a random number extractor differs from a conventional configuration, and the random number extractor acquires a probability distribution of measurement expectation values from information of a random number sequence for measurement basis selection used in the equipment, and at least one of information of imperfection of the equipment measured in advance, or information of imperfection of a quantum bit generator. Then, an estimation probability is calculated by using the probability distribution of the measurement expectation values, and a measurement result in a binary bit string output from the equipment is compressed by the calculated estimation probability to extract a secure random number.

Abstract: In carrying out a task that consumes data from a one-time pad, task inputs comprising at least first data and second data from the pad, are combined together to form an output from which the data used from the pad cannot be recovered without knowledge of at least one of the first and second data. The task concerned can be, for example, the encrypting of a message or the creating of an attribute verifier.

Abstract: A device is arranged to carry out security-related tasks using one-time pad data. The device has a memory for holding multiple one-time pads, each pad having a different security rating and being intended for use by the device in executing a task to that security rating. Provisioning of the pads with one-time pad data involves carrying out a process for obtaining new secret random data. This process has a security rating with the value of this rating varying according to the nature and parameters of the process concerned. The security rating of the process used to obtain the new secret random data is matched to that of the pad to be provisioned with one-time data, or the other way around, such that the security rating of the process is as least as good as that of the pad to be provisioned.

Abstract: Secret random data is distributed to a plurality of devices to provision them with new one-time pad data for use in interacting with apparatus holding the same one-time pad data. This distribution is effected by provisioning a first device with a block of secret random data that is, or will become, available to the apparatus. Part of the secret random data is then distributed from the first device to one or more other devices in a hierarchical distribution pattern headed by the first device. Each device, other than those at the bottom of the distribution hierarchy, retains part of the secret random data it receives and passes on the remainder. Each device uses that part of the secret random data it has retained to provide the device with new one-time pad data. A method is also provided for tracking service usage based on the distributed one-time pad data.

Abstract: A quantum key distribution (QKD) system is provided that makes use of a quantum signal of polarized photons and comprises a QKD device and complimentary QKD apparatus. The QKD device has a QKD subsystem comprising one of a QKD transmitter and receiver for inter-working with a complimentary QKD receiver or transmitter of said apparatus. The device also has an alignment subsystem arranged to wirelessly interact with the QKD apparatus to enable generation of user feedback and/or adjustment signals for use in aligning the QKD transmitter and receiver such that the QKD transmitter is pointing at the QKD receiver and the polarization axes of the QKD transmitter and receiver are aligned.

Abstract: A device stores one-time pad data for use in carrying out various tasks. In order to preserve the ability to carry out important tasks that require the use of one-time data, use of the one-time pad data held by the device is controlled such that an amount of this one-time pad data is only usable by a predetermined set of important tasks comprising at least a replenishment task for replenishing the device with one-time pad data.

Abstract: A method of establishing a shared secret random cryptographic key between a sender and a recipient using a quantum communications channel is described.

Abstract: A quantum key distribution (QKD) method involves the sending of random data from a QKD transmitter to a QKD receiver over a quantum signal channel, and the QKD transmitter and receiver respectively processing the data transmitted and received over the quantum signal channel in order to seek to derive a common random data set. This processing is effected with the aid of messages exchanged between QKD transmitter and receiver over an insecure classical communication channel. The processing concludes with a check, effected by an exchange of authenticated messages over the classical communication channel, that the QKD transmitter and receiver have derived the same random data set. At least some of the other messages exchanged during processing are exchanged without authentication and integrity checking. A QKD transmitter and QKD receiver are also disclosed.

Abstract: Various method and system embodiments of the present invention are directed to executing bit-commitment protocols. In one embodiment of the present invention, a method for executing a bit-commitment protocol for transmitting a bit from a first party to a second party comprises preparing a three qubits are entangled in a W-state, and storing a first of the three qubits in a first storage device controlled by the first party, a second of the three qubits is stored in a second storage device controlled by the second party, and a third of the three qubits is stored in a third storage device controlled by a third party. The bit is revealed to the second party by transmitting the first and third qubits to the second party and measuring the states of the three qubits to which of the entangled W-states the three qubits are in.

Abstract: A secure transaction method is provided for publicly-accessible transaction terminals. The method uses quantum key distribution (QKD) between a hand-portable QKD device and a complimentary QKD apparatus incorporated the transaction terminal. After the QKD device has been brought up to the transaction terminal, the QKD device and the complimentary QKD apparatus of the terminal are is used to provide the device and terminal with new secret shared random material. The new secret shared random material is then used to establish a secure classical communication channel between the device and transaction terminal for conducting a transaction. An ATM terminal and POS terminal that use quantum key distribution are also disclosed.

Abstract: Various method and system embodiments of the present invention are directed to executing bit-commitment protocols. In one embodiment of the present invention, a method for executing a bit-commitment protocol for transmitting a bit from a first party to a second party comprises preparing a three qubits are entangled in a W-state, and storing a first of the three qubits in a first storage device controlled by the first party, a second of the three qubits is stored in a second storage device controlled by the second party, and a third of the three qubits is stored in a third storage device controlled by a third party. The bit is revealed to the second party by transmitting the first and third qubits to the second party and measuring the states of the three qubits to which of the entangled W-states the three qubits are in.

Abstract: A method and apparatus for quantum information processing is disclosed in which logical qubits |0>L and |1>L are respectively encoded by different near orthogonal coherent states |?> and |?>, where <?|?>=0, |?> and |?> being the computational basis states for the qubits, for example, in which logical qubits |0>L and |1>L are respectively encoded by different ones of the vacuum state |0> and a multi-photon optical coherent state |?> which states are the computational basis states for the qubits. This provide an efficient scheme for linear optics quantum processing which is deterministic and for which qubit readout can use homodyne detection which is highly efficient. The invention finds application in quantum computation and quantum communication.

Abstract: A device is arranged to carry out security-related tasks using one-time pad data. The device has a memory for holding multiple one-time pads, each pad having a different security rating and being intended for use by the device in executing a task to that security rating. Provisioning of the pads with one-time pad data involves carrying out a process for obtaining new secret random data. This process has a security rating with the value of this rating varying according to the nature and parameters of the process concerned. The security rating of the process used to obtain the new secret random data is matched to that of the pad to be provisioned with one-time data, or the other way around, such that the security rating of the process is as least as good as that of the pad to be provisioned.

Abstract: A method and apparatus for quantum information processing is disclosed in which logical qubits |0>L and |1>L are respectively encoded by different near orthogonal coherent states |&bgr;> and |&agr;>, where <&agr;|&bgr;>=0, |&agr;> and |&bgr;> being the computational basis states for the qubits, for example, in which logical qubits |0>L and |1>L are respectively encoded by different ones of the vacuum state |0> and a multi-photon optical coherent state lot>which states are the computational basis states for the qubits. This provide an efficient scheme for linear optics quantum processing which is deterministic and for which qubit readout can use homodyne detection which is highly efficient. The invention finds application in quantum computation and quantum communication.